Question about lathe tool holder insert

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I was given a tool holder for my lathe, it has the carbide insert # 321 (I think) triangle I.C.=3/8 and 1/8" thick. The insert is held in the 1/2" square tool by a cap screw (I think they call it) on top and a hex screw on the bottom. this bottom screw appears to thread into the center hole of the carbide insert. question is, DOES IT??? I have tried to unscrew that bottom screw with out any luck, busted a allen wrench trying. Is that center hole in the insert threaded or what????
Reply:Pics would help, If it's a TNMG321 insert it may be either a cam (eccentric pin) or tilted screw that presses the insert against the back of the seat. The eccentric pins can be tightened enough you have to break the insert to get them apart.Matt
Reply:Does the tool have any markings on it, perhaps the maker (e.g. Valenite) and a model number?
Reply:As the others have essentially stated, it is likely that the one on the bottom is designed to "seat" the insert and the other one is designed to hold it in place. That is a very general design of many insert type lathe bits. Pictures would definitely help. Best regards, Allanaevald
Reply:Short answer...have any of you actually seen an insert with threads?Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:tool is MTGNL08-2A...top and bottom photo...It can't be seen in the photo but looking at the top i can see the tip of the underside screw flush with the top of the insert (thru center hole) Attached Images
Reply:here is the other side... Attached Images
Reply:We have tons of those holders at the shop..Sometimes you have to use a allen wrench in both ends to get the clamp un-done..They can be a pain and when you use a new insert only tighten it down a "Little Bit"No need for torque wrenches here......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:That one is made by Dorian Tool and is shown  in the link below. I looked on the Dorian site and found its listing but couldn't find a good picture or description of the screw arrangement. The front screw looks to me like a cam-lock type which both pushes the insert backwards and pulls it down too due to the angles involved. Anyway, here's the Picture: http://www.travers.com/product.asp?R...606-55-615-545Here is the Dorian site:http://www.doriantool.com/doriantool/index.php
Reply:The bigger screw on top came loose, i wiggled the insert out of the holder, but the smaller screw (thru the center hole) will not budge, now i got the hex head rounded and the allen wrench barely grabs....Now i'm really screwed maybe heat will loosen it up.....
Reply:Why are you even trying to remove that screw? Its only purpose should be for locating the insert in the holder and need not be removed when swapping out inserts. If you haven't broken it already, step away from the tool before you 'fix' it permanently.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:I was telling myself the same thing. but why did they include a special allen wrench for the bottom screw if it never needs to be turned?  but you may be right......actually i have no choice now that i  "FIXED"  it.....
Reply:Can you show a  picture of the top with the clamp removed, focusing on the center of the insert, or on the pocket beneath it if only the clamp held the insert in so it's now removed?